Unfortunately, there is no proven screening method, either blood test or radiological study, for patients who have been exposed to asbestos, at least for early detection of mesothelioma. If you are or have been a smoker and also have been exposed to asbestos, screening with chest CT scans for early detection of lung cancer may be indicated. Select centers in the United States, Canada, and Australia are all conducting clinical trials on early detection methods for mesothelioma. More recently, investigators have assessed the use of several blood markers in an attempt to detect mesothelioma earlier than conventional methods for people with a history of asbestos exposure. These tests include measurements of serum osteoporin, levels of the soluble mesothelin-related protein (which is elevated in the blood in about 75% of patients at the time of mesothelioma diagnosis), and the newly developed Mesomark assay that evaluates the levels of soluble mesothelin-related proteins released by mesothelioma cells (with higher levels of protein detected in cases with larger tumor volumes). All of these tests, however, are not considered standard at this time but hold great promise for being a more widely used screening test in the future.